Assessment of depression before and after inpatient rehabilitation in COPD patients: Psychometric properties of the German version of the Patient Health Questionnaire (PHQ-9/PHQ-2)

PHQ-9 and PHQ-2 fulfill important psychometric criteria (factorial validity, invariance, reliability) for measuring depression in COPD. The results support their use in clinical practice to assess severity of depression. Diagnostic accuracy to identify major/minor depression of both instruments should be examined in future studies.